1. The cell membrane
One of the most important parts of the cell is its Membrane, which separates the cell from its surroundings.
All cells are surrounded by a thin flexible barrier known as the Cell Membrane.
The cell membrane Controls what comes out and in of the cell. It also provides protection.
The composition is a double layered sheet called a Bi-lipid layer.
This lipid bi-layer is made up of two layers of Lipids (fats)

3. The cell membrane
The lipid bi-layer is what gives cell membranes a unique structure that forms a strong barrier between the cell and its surroundings.
In addition to lipids most cell membranes contain Protein molecules that are embedded in the lipid bi-layer.
There are also receptor molecules that are attached to the protein molecules.

4. Protein Channels
The proteins act as pumps and channels moving materials into and out of the cell and act as receptor molecules for any hormone or other chemical message that need to get into the cell.
The carbohydrates act like chemical Reading cards allowing cells to communicate with each other.

5. Look at the roots of the protein labels (hydrophilic & hydrophobic)
Look at the roots of the protein labels (hydrophilic & hydrophobic). What do you think they mean?

6. Passage of materials through the cell membrane…
What does the cell membrane do?
1. It protects the cell
2. It allows things in and out of the cell
3. It is Semi-Permeable (not everything can get across it)
4. It has 2 layers (It is like a protein sandwich) 5. The proteins are for transporting things across
LIPID
PROTEIN

7. DIFFUSION
Diffusion is the movement of materials from a high concentration to a low concentration until there is equilibrium (no energy is used to do this).

8. Why does diffusion occur?
The reason for this is so all the molecules can be in equilibrium.
Diffusion can also only occur across a cell membrane if there is a concentration gradient. (This is when material is higher on one side of the membrane than on the other).

9. Facilitated Diffusion is when protein channels in the cell membrane help the movement of molecules across the membrane.
Osmosis is the diffusion of Water across a membrane from High to low concentration.
[[No Energy used]]

10. Diffusion low  high inside cell fat fat fat fat outside cell fat fat
Which way will fat move?
inside cell
fat
fat
fat
low
high 
fat
outside cell
fat
fat
fat
fat
fat
fat

11. Diffusion sugar sugar sugar sugar sugar sugar  sugar sugar sugar
Which way
Will sugar
Move?
sugar
low 
high
sugar
sugar
sugar
sugar
sugar

12. What are the effects of Osmosis?
If you place a cell in a solution (mixture of 2 substances) three things can happen:
1. ISOTONIC SOLUTION
When the concentration of water is the same inside and outside cell
2. HYPOTONIC SOLUTION
When there is a higher concentration of water outside cell, so water moves into cell
3. HYPERTONIC SOLUTION
When there is a higher concentration of water inside cell, so water moves out of cell

13. Isotonic Solution Isotonic Solution Balanced conditions
no difference between cell & environment
example: blood
problem: none
water flows across membrane equally, in both directions
volume of cell doesn't change

14. Hypotonic Solution Hypotonic Solution Freshwater a cell in fresh water
example: Paramecium
problem: gains water, swells & can burst
water continually enters Paramecium cell
solution: contractile vacuole
pumps water out of cell

15. Hypertonic Solution Hypertonic Solution Saltwater a cell in salt water
example: shellfish
problem: lose water
plasmolysis in plants
shrinking cell
solution: take up water

16. Methods of Transport
Passive transport: movement from High to low concentration. No energy is used.
This is also called Simple diffusion
Active transport: movement from low to high concentration. A. needs energy B. opposite of simple diffusion

17. Now add the following words to your explanation:
Active Transport
Analyze this animation. Explain what you see happening.
Now add the following words to your explanation:
Solution
Molecules
Cell membrane
Protein channel
ATP
Active Transport
High concentration
Low concentration

18. Do the animations below portray active or passive transport
Do the animations below portray active or passive transport? How do you know?
SIMPLE DIFFUSION Move from HIGH to LOW concentration
“passive transport”
no energy needed

19. Do the animations below portray active or passive transport
Do the animations below portray active or passive transport? How do you know?
ACTIVE TRANSPORT Cells may need molecules to move against concentration difference
need to pump “uphill”
from LOW to HIGH using ATP
protein pump
requires energy ATP
ATP

20. Transport Summary diffusion facilitated diffusion active transport
Analyze the three forms of transport across a membrane below. Identify and Explain the forms of transport for each red arrow!
diffusion
facilitated diffusion
ATP
active transport

21. Transport Vocab Pinocytosis- cell drinking-engulfing small particles.
Phagocytosis- cell engulfing- Lysosomes fuse with a bacteria for digestion
Cyclosis- Movement of the cytoplasm